The prior art discloses programmable logic controllers (PLCs) that can be used in automation engineering to program and automatically actuate actuators, particularly end effectors and provision systems, and also sensors and other functional units of a machine or installation. A functional element of this kind, which is actuatable by a programmable logic controller, in principle, is generally referred to both individually and in a combination, here and subsequently, as an input/output module. Conventionally, these programmable logic controllers have been provided by devices and electronic arrangements provided specifically for this purpose. Habitually, such programmable logic controllers communicate with the input/output module that they are configured to actuate via a bus, such as e.g. a field bus.
In the meantime, programmable logic controllers whose functionality is provided by a computer program executed on a computer are also known. Such a computer program can be referred to as a PLC computer program, the system operated using such a PLC computer program being able in turn to be referred to as a soft PLC as a whole. There is thus no further provision for special hardware for the programmable logic controller, but rather its functionality is formed by a computer program that runs on a conventional computer or on an industrial PC or embedded PC tailored to the automation environment. For the purpose of actuating the input/output modules, such a computer may accordingly likewise be connected to a field bus.
The prior art and specifically EP 1 586 967 A2, on which the present invention is based, also disclose expansions through software for such a PLC computer program. One such known expansion can e.g. be used to allow communication with a specific device by a driver or the like. However, the expansions presented in this prior art are expansion modules such as e.g. dynamic program libraries or
DLLs (dynamic-link libraries) that can be addressed or incorporated by the PLC computer program. They are thus ultimately under the software control of the PLC computer program in this case. There is no provision for control of the programmable logic controller for software purposes by this expansion.
When automation cells are part of an automation system, it is habitually the case that an input/output module actuated by a programmable logic controller is arranged on a manipulator, which is e.g. a multi-axis robot. Specifically, the input/output module may be arranged at the tool center point (TCP) of the manipulator.
Such a manipulator habitually has its movements actuated by a numerical controller, here and subsequently referred to as an NC controller. This NC controller can also, in principle, be provided by a computer program executed on a computer. The provision of the input/output module on the manipulator closely relates the activities performed by the input/output module—which are prescribed e.g. by the PLC computer program—and the movements of the manipulator—which are in turn controlled by the NC controller.